Barcelona star Lionel Messi has agreed to a new contract, the Camp Nou club has confirmed.

Messi extended his stay with the Catalan club until 2018 last year, but has long been anticipated to sign an improved deal to make him the highest paid player in world football.

Lionel Messi (AP Photo)

The Argentinian was involved in a war of words with Javier Faus in December after the club's vice president said he saw no reason why Barca should improve Messi's contract "every six months."

Messi hit back by branding Faus as a businessman "who knows nothing about football."

After a season that has seen Messi reach the 40-goal mark for the fifth straight year, the 26-year-old has now been rewarded with a new contract.

He is expected to sign the deal in the coming days.

A statement on the Barcelona website read: "FC Barcelona has reached an agreement to adjust the terms in the contract binding Leo Messi to the club as a professional first team player. The revised and updated contract will be signed over the next few days."

It has been a campaign of frustration for Messi, despite his fine goalscoring record, due to a number of injuries including a hamstring problem that kept him out of action for almost two months from November to early January.

Barca has been below par for much of the campaign in both domestic and European competition, losing the Copa del Rey final to Real Madrid and suffering a quarterfinal exit from the UEFA Champions League at the hands of Atletico Madrid.

However, Gerardo Martino's men will have the chance for revenge on Sunday as they host Atletico in a Spanish title decider knowing that victory will secure a 23rd Liga crown and Messi's 22nd trophy with the club.

Martino implied that the announcement of Messi's new deal will relax his side ahead of the mammoth clash with Diego Simeone's team.

"I'm sure it will be relaxing for Leo and the club if they can have the best player in the world staying with the club," Martino said. "It'll be good for him and good for the club because he'll be able to bring that sense of relaxation out onto the pitch with him."